Numerous solar collectors have been devised, many of which are of the tracking type to enable the collector to remain substantially perpendicular to the solar position by selectively altering its orientation in response to the solar position. Some of these known devices compensate for the compound movement of the sun, daily from horizon to horizon, and seasonally by means of a progressive elevational change. For this purpose, various controls are utilized, such as solar cells or other photovoltaic devices, or clock mechanisms, to control the tracking movement and hence orientation of the reflector or concentrator. While most known solar concentrators operate fairly satisfactorily with respect to their capability of concentrating and collecting solar energy, nevertheless many of these devices are extremely complex and cumbersome with respect to the structure and hardware involved. More specifically, in order to provide a reflector or concentrator of rather large size so as to permit effective collection of substantial solar energy, such concentrators are often divided into several portions which are individually movable, which thus greatly increases the drives and controls required for the overall assembly. In the alternative, the rather large concentrators are often fixed or have only limited movement variety, and this in turn additionally restricts the effectiveness of the concentrator. When an attempt is made to provide a large reflector with the capability of both daily and seasonal tracking movement, then the resulting support structure generally becomes extremely complex, costly and cumbersome, whereby the resulting solar device is of prohibitive cost, and is also of undesirable size and creates an unsightly appearance.
Accordingly, it is an object of the present invention to provide an improved solar concentrator which effectively overcomes many of the undesirable advantages associated with prior such devices, and which still permits suitable tracking, both daily and annually, so as to maintain the concentrator in the desired relationship relative to the solar position. More specifically, it is an object of this invention to provide an improved solar concentrator, as aforesaid, which permits utilization of a rather large reflector or mirror array formed substantially of a parabolic configuration to permit efficient concentration and collection of solar energy, which mirror array is suitably movably supported so as to undergo the desired daily horizon-to-horizon tracking of the solar position, and which can also be suitably angularly adjusted to compensate for seasonal elevational changes in the solar position. At the same time, the mirror array or reflector in the improved concentrator of this invention, even though of substantial size, is supported by an improved frame structure, specifically an open geodesic dome or shell having the mirror array movably disposed therein, so that the resulting solar concentrator thus possesses substantial strength and rigidity while utilizing a supporting frame which possesses minimum structural complexity, which can be manufactured and assembled in a simple, efficient and rather inexpensive manner, which provides the necessary strength and rigidity to withstand environmental forces while still additionally permitting the mirror array to be movably supported as desired, and which is considered more aesthetically acceptable than many of the prior devices. This improved solar concentrator, in addition to incorporating the desirable structural and functional advantages explained above, additionally enables very efficient and effective concentration of the solar energy to permit efficient utilization thereof, and additionally enables the mirror array to effectively track or follow the solar movement in a simple and efficient manner so as to permit the desired efficiency in the collection of solar energy.
Other objects and purposes of the invention will be apparent to persons familiar with devices of this general type upon reading the following specification and inspecting the accompanying drawings.
In the solar concentrator of this invention, there is provided a support frame formed substantially as a geodesic dome, which dome effectively comprises an open ball-like framework formed by a plurality of interconnected triangles, each triangle being formed by three elongated rodlike struts. A gridlike support is movably disposed within the geodesic dome and mounts thereon an array of mirrors which define a substantially parabolic reflecting and concentrating surface. The support grid has a mast fixed thereto and projecting outwardly from the mirror array substantially along the axis of generation of the parabolic surface. A target is mounted at the free end of the mast, normally in the vicinity of the focal point of the mirror array, for collecting the solar energy. The target, in a preferred embodiment, employs a spirally wound coil having a fluid flowing therethrough. The mirror array is hingedly supported for limited angular displacement about a first axis which extends substantially diametrically of the dome for permitting the mirror array to be angularly displaced to compensate for seasonal elevational changes in the position of the sun. The mirror array is also movably supported for angular displacement about a second axis which also extends diametrically of the dome and is substantially perpendicular to, and approximately intersects, the first axis. The mirror array is angularly displaced through a substantial angular extent about this second axis to permit daily tracking of the sun from horizon to horizon. A pair of drive mechanisms, suitably controlled by a control system employing both phototransistors and a timer, are provided for individually controlling the angular displacement of the mirror array about the first and second axes. The second axis is defined by an elongated polar shaft which extends diametrically across the dome and is suitably rotatably supported thereby. The gridlike frame for the mirror array is in turn hingedly supported on the polar shaft by a bearing arrangement located substantially at the midpoint thereof, which midpoint also effectively defines the midpoint of the dome, for additionally permitting the mirror array to be angularly displaced about said first axis.